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  1. #1
    Senior Member cblaster's Avatar
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    Changing gear ratios

    I'm currently riding with a 48:18 gear ratio - 72 gear inches. The thing is, I only have 3 skid spots with this ratio. I'd like to get either a 17t or 19t cog so that I don't have to worry about my tire so much, but either way, I'm going to lose or gain 4 gear inches. Is it going to make that much of a difference that I can really feel while riding, or will those 4 gear inches be something that I can easily overlook and shrug off?

  2. #2
    blah onetwentyeight's Avatar
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    You'll be able to feel the difference. It wont be huge, but it will be noticable. FWIW I prefer erring on the side of spinny.

  3. #3
    Senior Member cblaster's Avatar
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    Yeah that's the problem, I don't know if I want to spin more, at the same time, I don't want to lose any "acceleration" out of traffic lights.

  4. #4
    Senior Member 1fluffhead's Avatar
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    If you like 72 GI, change everything and go to 46x17. You will get the skid patches and still have what you want.
    Quote Originally Posted by diff_lock2 View Post
    so what if it's custom, are you suddenly NOT a jackass?

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    Fixed-gear roadie JacoKierkegaard's Avatar
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    If it's pretty flat where you are, go for 17. If it's hilly, go for 19. I run 48x16 in a flat area and I find that to be a very reasonable ratio, although I do tend to prefer mashing big gears to spinning a fast cadence.

    46x17 as mentioned above is a good idea too if you really think your current ratio is ideal for you.
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  6. #6
    blah onetwentyeight's Avatar
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    Quote Originally Posted by cblaster View Post
    Yeah that's the problem, I don't know if I want to spin more, at the same time, I don't want to lose any "acceleration" out of traffic lights.
    then go spinny. you can get up to speed faster with a smaller gear ratio and a good spin than trying to push something heavy. Its the same reason a geared rider would shift down to something easier when approaching a stop light, get up to speed, then shift to a heavier gear to keep speed at a more easily maintained cadence.

  7. #7
    ECR Meepers's Avatar
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    i also agree with 46 x 17. that's what i am running. i wouldn't want to go any lower 73 GI. i noticed a huge difference when i dropped from 48 x 16 (81 GI). But i moved and i now had huge hills to contend with. 17 skid patches, 32 if you can go either way.
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  8. #8
    Senior Member AidanJ's Avatar
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    i run 46x17 in my (mostly) flat city, and its great, if anything i'd change it to something a little harder.

  9. #9
    blah 00soul's Avatar
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    Quote Originally Posted by 1fluffhead View Post
    If you like 72 GI, change everything and go to 46x17. You will get the skid patches and still have what you want.
    or maybe just a 49t chainring. it's around the same GI

  10. #10
    Senior Member cblaster's Avatar
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    Quote Originally Posted by JacoKierkegaard View Post
    If it's pretty flat where you are, go for 17. If it's hilly, go for 19. I run 48x16 in a flat area and I find that to be a very reasonable ratio, although I do tend to prefer mashing big gears to spinning a fast cadence.

    46x17 as mentioned above is a good idea too if you really think your current ratio is ideal for you.
    That's why I'm not sure what to go with, because at the beginning and end of my ride, there are hills, but the middle of my ride (about 70% of it) is a flat, urban area. I do like my current set-up but I'll probably go 48:17 because I don't have the cash for a new cog and chainring right now. I'd rather take on something a little heavier than lighter.

    Thanks for the input everybody.

  11. #11
    Spinning @ 33 RPM Glynis27's Avatar
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    I have run 60 GI (lol) for the past 2 years on my getting-around bike. Very low gearing, but I have other bikes for going fast and I am able to maintain 18-20mph no problem. Just this past weekend I switched to 67 GI hoping to get me in the 20-22mph cruising range. So far, I am actually a tiny bit slower and my quads burn like crazy. I feel like I have a hard time getting on top of the gear into a cadence I am comfortable with. I am thinking/hoping that my legs will just get used to it soon.

    An extra 4 GI sounds like very little, but if you are already around your limit, that might just push you a bit too far. I would try to stay as close to your current ratio as possible, unless you are really spinning out a lot.
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  12. #12
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    going from a ~70 to ~75 is very noticeable. get a 47 or 49 ring if you want more similar GI.
    i won't deny it i'm a straight ridah

  13. #13
    King of the Hipsters
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    Prime number sprockets give prime number skid patches.

    That said, stop skidding.

    I've ridden every sprocket and chainring combination imagineable, sort of a hobby, from 82" to 48", and I presently ride with 60".

    Have I learned to spin?

    Yep.

    I get around town just as fast at 60" as I ever did at 82".

    For awhile I had a 15 mile one way commute on a perfectly flat rural road, and I went back to 82" for that commute.

    But for general bombing around in traffic, I recommend going way down in gear inches and learning to spin.

    My normal commute of 7.5 miles includes a few hills, and someone in San Francisco might not think much of them, and someone from Flatland might find them intimidating.

    At 60 gear inches, for this commute, I average 18.0 mph in traffic; and, at 82 gear inches I average 19.6 mph.

    However, at 60 gear inches I have a lot more fun than I do at 82 gear inches, and I feel safer and more in control.

    At 60 gear inches I don't skid and I don't need a brake.

    Not for everyone.

    Think about it.

  14. #14
    Senior Member mihlbach's Avatar
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    What you need is a 49t chainring. A chainring swap will not change your gear ratio as much, and will give you 36 skid patches.

  15. #15
    Senior Member mihlbach's Avatar
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    Quote Originally Posted by Ken Cox View Post

    I get around town just as fast at 60" as I ever did at 82".

    Are you sure about that? I fluctuate between 76" (winter) and 81" (summer). Any lower and I'd be spinning 200+ rpms at the speeds I hit on hill descents. Something as low as 60" would take several MPH off my average speed and would making going downhill a nightmare.

    Edit: Well, OK, you said "around town". Out on the open road, 60" is just too low.

  16. #16
    Al noisebeam's Avatar
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    As others said you will feel it. But more importantly after a month at most you will have adapted to it and it will feel normal.

  17. #17
    King of the Hipsters
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    Quote Originally Posted by mihlbach
    Are you sure about that? I fluctuate between 76" (winter) and 81" (summer). Any lower and I'd be spinning 200+ rpms at the speeds I hit on hill descents. Something as low as 60" would take several MPH off my average speed and would making going downhill a nightmare.

    Edit: Well, OK, you said "around town". Out on the open road, 60" is just too low.
    Yes, and for that reason on my 15 mile flat rural road commute I went back up to 82".

    I enjoyed that commute enormously because of the opportunity to hit a constant rhythm and just fly.

    And, I can still do the hills at 82 gear inches, but for traffic I find I the ability to accelerate and decelerate effortlessy sooo nice.

    Not only accelerate and decelerate, but 60" makes low speed maneuvering much easier.

    And so, once I awakened to the virtues of low gear inches, I took it upon myself to learn to spin in order to make up for the obvious shortcomng of low gear inches...low speeds.

    Now, at spin rates that formerly made me bounce, I don't even think about it.

    I would not have learned to spin at these rates, though, if I had not wanted to make 60" practical.

    As for hill descents, I don't try to go silly fast any longer.

    I go downhill about as fast as I go on the level, by preference (safer).

    I have no doubt that several of my fellow forumites who ride in the high 70's and low 80's can outspin me.

    For myself, though, I would not have put the effort into learning to spin if not for the desire to make 60" practical.

    And, like I said, for a 7.5 commute I've only given up 1.6 mph on average, and one extra stoplight would do that.

    So think of 60" as an option; and, an option that will take some study and work in order fully enjoy the advantages.

    Otherwise, everyone would ride 60" instead of 72-78".

    =====

    And one more point: at 60" I don't need a brake and I don't need to skid.

    My tires last a long time.

  18. #18
    HAMMER DOWN SSBully's Avatar
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    Get a 17 and a 19t and put one on each side! If you feel too spinny, switch to the other one! If you're feeling tired, and don't want to work as hard, switch it back!

    The best solution, IMO is a 46x17 though.
    Aaaaawwwww look at all of those cute gears and shifters and cables and derailleurs! Isn't that special! Overall it's a sweet bike! I do have one question though...........................Do they make them for men?

  19. #19
    Spinning @ 33 RPM Glynis27's Avatar
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    Quote Originally Posted by SSBully View Post
    Get a 17 and a 19t and put one on each side! If you feel too spinny, switch to the other one! If you're feeling tired, and don't want to work as hard, switch it back!

    The best solution, IMO is a 46x17 though.
    Not a bad idea.
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  20. #20
    Senior Member cblaster's Avatar
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    I'm actually gonna ride over to my LBS tomorrow and see if they have any 47 or 49 tooth chainrings, that way I'll only lose or gain ~1.5 gear inches. I'll keep my 18t cog, and with a 47t or 49t chainring I'll have 18 skid patches either way. Hopefully, they have one under $30.

  21. #21
    HAMMER DOWN SSBully's Avatar
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    Quote Originally Posted by cblaster View Post
    I'm actually gonna ride over to my LBS tomorrow and see if they have any 47 or 49 tooth chainrings, that way I'll only lose or gain ~1.5 gear inches. I'll keep my 18t cog, and with a 47t or 49t chainring I'll have 18 skid patches either way. Hopefully, they have one under $30.
    If you're going to get a new chainring, get a new cog as well and go 46x17 like everyone's already said! lol
    Aaaaawwwww look at all of those cute gears and shifters and cables and derailleurs! Isn't that special! Overall it's a sweet bike! I do have one question though...........................Do they make them for men?

  22. #22
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    Might be an obvious answer, but dropping from 48 x 16 to 46 x 17 will require a shorter chain?

  23. #23
    * adriano's Avatar
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    Quote Originally Posted by oeuf View Post
    Might be an obvious answer, but dropping from 48 x 16 to 46 x 17 will require a shorter chain?
    if youre near the back of the ends, you need to take a link out.

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